MicroDexed is a compatible 6-operator-FM-synth based on the Teensy(-3.6/-4.x) Microcontroller. https://www.parasitstudio.de
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/*
Copyright 2019 Jean Pierre Cimalando.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include <math.h>
#include "porta.h"
#include "synth.h"
void Porta::init_sr(double sampleRate)
{
// compute portamento for CC 7-bit range
for (unsigned int i = 0; i < 128; ++i) {
// number of semitones travelled
double sps = 350.0 * pow(2.0, -0.062 * i); // per second
double spf = sps / sampleRate; // per frame
double spp = spf * _N_; // per period
const int step = (1 << 24) / 12;
rates[i] = (int32_t)(0.5f + step * spp); // to pitch units
}
}
int32_t Porta::rates[128];